INTERFACIAL CHARACTERISTICS OF MARINE ALGAE AND
BACTERIA USING ADHESION BASED ELECTROCHEMICAL SENSOR
Kovac, S., Center for Marine and Environmental Research, Rudjer Boskovic Institute,
10 001 Zagreb, kovac@rudjer.irb.hr
Ivosevic, N., Center for Marine and Environmental Research, Rudjer Boskovic
Institute, 10 001 Zagreb, ivosevic@rudjer.irb.hr
Svetlicic, V., Center for Marine and Environmental Research, Rudjer Boskovic
Institute, 10 001 Zagreb, svetlicic@rudjer.irb.hr
Zutic, V., Center for Marine end Environmental Research, Rudjer Boskovic Institute,
10 001 Zagreb, zutic@rudjer.irb.hr
Mixtures of biopolymers and microbial cells are typical of natural aquatic
environment such as seawater where they form biofilms at the interfaces and undergo
aggregation. The electrochemical sensor that we have developed enables a distinction
between cell adhesion and biopolymer adsorption.
We study the adhesion of phytoplankton and bacteria in presence of adsorption of
dissolved biopolymers at a model interface: seawater/dropping mercury electrode
where the interfacial forces can be controlled by applied potential.
Measuring parameters are frequency of cell adhesion, and the time of monolayer
formation at the electrode surface.
Upon impact of a D.tertiolecta cell with the interface a fast deformation occurs,
followed by rupture of its fluid membrane and spreading of the cell content on the
mercury surface. The electrical signal carries the information on all phases of the
adhesion process starting from the initial molecular contact to the spreaded film.
Marine bacteria adhere directly at the DME forming molecular contact, but because of
rigid cell wall and the smaller size the adhesion signals of individual cells can not be
resolved.
We have demonstrated that the cell attachment and biopolymer adsorption occur
simultaneously forming separated domaines in the initial film.